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motility, accommodation and nearfunctions. It is, of course, an invasivetechnique that is uncomfortable oreven distressing for the child.

The Mohindra technique is muchmore child-friendly and is also quick,since there is no waiting time fordrops to take effect. Accommodation

and near functions remain intact so acomplete eye examination can takeplace on the same occasion. Sinceaccommodation is equal in the twoeyes, binocular balance is assured.

The Mohindra technique relies onthe observation that, in total darkness,the eyes adopt a stable small amount

of accommodation (that can be

predicted) and this is equal in the twoeyes. As Mohindra takes place in totaldarkness, a few children might find itdisturbing, but with appropriatepreparation, this is rarely a problem.So, begin by explaining what is going

to happen. Position the child on aparent’s lap, or ensure that the parentin close by and in physical contactwith the child (to avoid the childjumping or sliding off the chair in thedark). Lower the lights gradually,

keeping the retinoscope light on thechild’s eyes all of the time (so that thechild always has something to see). If the child is nervous, remember to

keep talking all the time. Thetechnique should be performedmonocularly to prevent convergenceclues to the distance of the light from

stimulating accommodation. If you arenot using a trial frame, then simplycover one eye with the hand holdingthe lenses. A dimmed retinoscopelight will also minimise any stimulusto accommodate. When watching thereflex, wait for maximum pupil

dilation – if the pupils constrict, theeyes are accommodating. Neutralise

the reflex in the usual way. For a50cm (2.00D) working distance,Mohindra recommended subtracting1.25D, thus allowing for 0.75Daccommodation3. Saunders andWestall1 showed that this is notappropriate for children: they

recommend subtracting 0.75D forinfants under the age of two years(allowing for 1.25D accommodation),and 1.00D for children of two yearsand over (allowing for 1.00D

The measurement of refractive errorThe standard procedures of staticretinoscopy followed by ‘subjective’ isnot feasible for young children;

instead, the two techniques of cycloplegic and Mohindra retinoscopyare used. Studies show that the twogive equivalent findings in infants and

children,1,2 so the practitioner can beconfident in choosing either one.

Lynne Speedwell’s article‘Optometric examination of children’,(OT February 9 2007) dealt thoroughlywith guidelines for choice of cycloplegic drug, activation time etc.Cycloplegic refraction has the obvious

advantage of dilating the pupil,

making subsequent ophthalmoscopymuch easier. On the other hand, awidely dilated pupil gives rise toaberrations that can make retinoscopymore difficult. It is not always possibleto ensure equality of cycloplegia in thetwo eyes, especially if the child has

been reluctant to open his/her eyesduring instillation, so the binocular balance of the final prescription may be suspect. Cycloplegia prevents post-refraction assessment of ocular

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J. Margaret Woodhouse

Refracting young children is not difficult, but may require specialisedtechniques. Determining the significance of findings is more complex than foradult patients, as the refraction that can be considered 'normal' in children

varies with age. The impact of a refractive error on a young child'sdevelopment will depend on many factors such as accommodation. Thisarticle discusses the issues for optometrists dealing with young children.

Management of refractive error

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accommodation). Using these working

distance allowances, Saunders and

Westall showed that Mohindra givesthe same final refractive error ascycloplegia. If the optometrist works ata different distance, adjustments can be made accordingly.

The repeatability ofmeasurement of refractionThe ‘repeatability’ of an optometrictechnique is an important concept. Itis a description of the precision of themeasurement, and for clinicalpurposes, it allows the optometrist to

determine whether a visual or ocularfunction has changed over time. Forexample, if a child has a refractiveerror of +2.25D on one occasion, andat a six-month re-check refractionreveals +2.75D, has the refractive errorchanged? The repeatability gives theconfidence limits for recognising a realchange in visual function. For

refractive error, repeatability is arrivedat by measuring the error twice (with ashort time delay) in a group of subjects, and recording the difference

between the two occasions. Therepeatability co-efficient is 1.96 timesthe standard deviation of thesedifferences. In young children

(between six months and four years)the repeatability of both Mohindra andcycloplegic refraction (to the nearest0.25D) is ±0.50D1 i.e. 95% of alldifferences between refractions willfall within ±0.50D. This means that, inthe example given above, we can beconfident that the child’s refractive

error has not changed, as the observed

difference can be accounted for byvariability in the technique. We wouldneed to record an increase or decreasein refraction of 0.75D or more on thesecond occasion before we could beconfident that refractive error has

changed.It is worth noting that repeatability

of refraction for adult subjects(retinoscopy followed by subjective) isgenerally held to be ±0.50D4.Refraction of a child subject (by anexperienced observer) is as precise as

the refraction of an able adult.

The significance of refractive findingsAmongst young children, refractiveerror varies with age, in terms of both

infancy simply by the mean value,+3.00D, is clearly insufficient, since

higher amounts of hypermetropia andlow amounts of myopia are not at alluncommon. By school-age thedistribution is very different (the

figure shows ages 6-8, but in fact thedistribution is similar to this by age 4-5 years). Now the curve is far fromstatistically ‘normal’; there is a marked

peak around +1.50D hypermetropiaand the distribution is extremelynarrow. Myopia is rare, andhypermetropia is confined to +3.00Dor less. It is the process by whichchildren grow out of refractive errors

average refractive error and range orspread of errors, and Lynne

Speedwell’s article has alreadyintroduced the word‘emmetropisation’ to describe theexpected change in refraction over

time. In this article we will look inmore detail at normal and abnormalprogress in refraction, in order todevelop evidence-based guidelines for

the management of errors in practice.Classical data, represented by Figure

1 shows that, among newborns,refraction is widely distributed - infact the distribution is statistically‘normal’. Describing refraction in early

< Figure 1

Distribution of spherical refraction in young children (from Hirsch and Weymouth5 )

< Figure 2

Individual data from 7 children showing a change in refractive error between first examinationand 12-17 months of age (from Saunders et al8 )

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(of whatever sign) in infancy that isknown as emmetropisation. (For the

purposes of the following discussion,we need to consider ‘emmetropia’ asincluding low hypermetropia, thepeak of the 6-8 year curve in Figure 1.Research papers tend to defineemmetropia as a refraction within therange –0.25 to +1.00D or thereabouts).

Hypermetropic eyes, in general, are

small eyes and the observation that

hypermetropic eyes become lesshypermetropic as children grow isperhaps not surprising. Newborn eyeshave, on average, an axial length of 17mm6 while eyes of six year oldshave an axial length of 22.6mm.7 It isthe myopic eyes, which grow overall

and yet become less myopic, whichprovide (part of) the evidence thatemmetropisation is an active, ratherthan a passive, growth process.Further evidence comes fromlongitudinal studies, such as that

illustrated in Figure 2, which showemmetropisation taking place inindividual eyes. The higher the initialrefractive error, the greater the rate of change towards emmetropia. There is

also considerable evidence thatemmetropisation is a visually-driven

process; in animal studies refractiveerrors can be readily manipulated byusing spectacle or contact lenses toinduce optical blur9.

The story with regard to astigmatismin infancy is similar, although ratherless dramatic. The incidence of astigmatism (of 1.00D or more) may be

as high as 65% among young infants.

This largely disappears, so that byschool age only 4-8% of children willhave astigmatism of this value.10

Anisometropia (usually defined as adifference of >0.75D or >1.00D between eyes) is uncommon inchildren, although some studies

suggest that up to 25% of newbornsare anisometropic, outgrowing it overthe first few months as part of theemmetropisation process. By schoolage, only 3-4% of children will exhibitanisometropia.10 The association

between anisometropia andamblyopia/strabismus is well known.

So the refractive error that can beconsidered ‘normal’ in a child will bevery different at different ages, leaving

a dilemma for practitioners trying to

determine when to prescribe

spectacles. The American Academy of Ophthalmology publishes (as part of its ‘Preferred Practice Patterns’ series)the guidelines (see table 1) forprescribing spectacles.

However, the table carries the

following important note: Thesevalues were generated by consensusand are based solely on professionalexperience and clinical impressions, because there are no scientificallyrigorous published data for guidance.

Individual practitioners will have

very different opinions about whatlevel of refractive error requirescorrection. My task here is to discussthe published studies that may allowus to inject a little evidence into ourdecision-making.

Let’s begin by thinking about whatwe expect to be the benefits of refractive correction. These are

minimising the risk of defects such asstrabismus and amblyopia, providinggood visual function with a clearretinal image and improving binocular

function (including straighteningsquint). The last point was dealt within the article on binocular visionanomalies (OT , April 6). Practitioners

would presumably agree onprescribing for a hypermetropic childwho is already exhibiting strabismusand/or amblyopia.

The relationship between refractiveerror and strabismus is well known: intypical children there is a strongassociation between hypermetropia

and convergent strabismus, so some

attention has been paid in researchprojects to the management of hypermetropia in early infancy, beforesuch defects develop. In spite of expectations that correctinghypermetropia might be a useful

preventative measure, the Cambridgelongitudinal study producedinconclusive results in terms of prevalence of strabismus at age 3.5years between hypermetropic childrenwho had been corrected at a young age(9-12 months) and those left

uncorrected.11 However, correctionhad a positive impact on visual acuity by the age of 3.5 years and thereforereduced the prevalence of amblyopia.Studies, of course, use statistical

< Table 1 Modified from the American Academy of Ophthalmology guidelines for prescribingspectacles

* may reduce the amount by up to +2.00D, or if the cycloplegic prescription is ≥ +7.00D may reduce by up to +3.00D

Condition Refractive error (D)

Age 0-1 yr Age 1-2 yr Age 2-3 yr

Isometropia (similar

refractive error in both eyes)

Myopia >-4.00 >-4.00 >-3.00

Hypermetropia -

no strabismus *>+6.00 >+5.00 >+4.50

Hypermetropia with esotropia >+2.00 >+2.00 >+1.50

Astigmatism >3.00 >2.50 >2.00

Anisometropia

Myopia >-2.50 >-2.50 >-2.00

Hypermetropia >+2.50 >+2.00 >+1.50

Astigmatism >2.50 >2.00 >2.00

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probabilities to describe results; as far

as advising for an individual child is

concerned, there are no certainties. Soshould we be prescribing for allhypermetropic infants in order tomaximise acuity in childhood? Arethere any dangers in such anapproach?

Animal studies would suggest thatcorrecting refractive errors at a youngage is likely to impedeemmetropisation, (in effect ‘fooling theeyes into thinking they are alreadyemmetropic’) and one study withchildren supports this12. On the other

hand, the Cambridge longitudinalstudy showed that spectacle correction(in this case a partial correction –more of this later) did not influencethe final level of refractive errorcompared to an uncorrected controlgroup, although the corrected groupwere slower in achievingemmetropisation.11

More usefully for the eyecarepractitioner, several studies suggestthat children who go on to developstrabismus and amblyopia have not

shown the usual reduction inrefractive error prior to the onset of the defect13,14. This means thatmonitoring a refractive error in a

young child will be more predictive of risk for strabismus and amblyopiathan a single measure of refractiveerror at one age. If refractive errorreduces over time, risk is minimal,whereas if there is no such reduction,risk is heightened. Restrictingcorrection of hypermetropia to those

children whose refractive error does

not reduce over time would appear to be the best strategy.

Two questions now arise. Whenmonitoring refraction in a young child,at what interval should retests takeplace, and how much change in

refraction towards emmetropia shouldwe expect? If refraction changed at asimilar rate in all children in a linearfashion, we could develop preciseguidelines for monitoring. But this isnot the case. The longitudinal data inFigure 2 (p31) show that the rate of

change of refraction depends on theinitial level of ametropia. Since inclinical practice we do not see allchildren at the same very youngstarting age, we are unlikely to know

practice, but do we consider why thisshould be? Figure 1 (p31) seems to

explain this: the mean refractive errorin children is hypermetropia - byschool age the mean is around +1.50D.It may, therefore, seem intuitive thatreducing a hypermetropic correctionto leave a child in the ‘usual state of

affairs’ is appropriate, but we have noexperimental evidence to show that.How do children cope with thisrefractive error? The answer, of course,is accommodation. Small amounts of hypermetropia are not detrimental if the accommodative system

compensates for the ‘error’. We expectchildren to have ampleaccommodation to readily overcomelow to moderate hypermetropia. Thegeneral finding of good visual acuityin children and young adults with lowhypermetropia argues that the ‘defect’is habitually overcome byaccommodation. But should we take

this for granted? By far the mostcommon refractive status in school agechildren, as Figure 1 shows, is lowhypermetropia. Yet we would consider

ourselves negligent if we didn’tmeasure refractive error in every childpatient, but simply assumed it. Why,

then, do we often assumeaccommodation is ample? Fewpractitioners routinely measureaccommodation, but I am going toargue for its inclusion in routinepractice, in order to allow theoptometrist to make informeddecisions about refractive correction.

There is evidence for the importanceof accommodation measures; a large-

scale longitudinal study of refractionin childhood reports thataccommodative deficits are commonamongst hypermetropes15.

Measurement of accommodationAccommodation in adults is usually

measured by the subjective push-uptechnique to give the amplitude. Sincechildren may not understand theconcept of blur, this is not a feasibleway to test. A ‘push-down’ techniquemay be a viable alternative: show a

small picture target, letter or wordwithin a centimetre or two of thechild’s eye. Gradually move the targetfurther away, asking the child to namethe target as soon as s/he can.

the ‘initial refraction’. For ease of

analysis Saunders et al (1995) plotted

only two points for each child in thegraph, but the apparent linearreduction in hypermetropia is anillusion. Most studies show thatrefraction changes at a faster rateduring the first year of life than during

subsequent years. And, of course, as inall aspects of development, childrendiffer amongst themselves in growthrate. So it is not possible torecommend a fixed re-test interval:practitioners need to consider thefactors in each case: the age of child at

first test and the refractive error, aswell as other risk factors such as binocular status and family history, indetermining the date of the next test.How much change in refraction toexpect will also depend on age at first

test. The ±0.50D repeatability limits of

the refraction procedure must also be

borne in mind in interpreting findings.If refractive error is not proceeding

in the emmetropic direction, or a childarrives at the age at whichemmetropisation is consideredcomplete (four years) what level of

hypermetropia constitutes a risk ordefect? When correcting, how much of the hypermetropia should becorrected? The American Academy’stable (table 1) carries another note: *when correcting hypermetropia withno strabismus, the consensus is that

the prescription may be reduced by upto +2.00D, or when the refractionexceeds +7.00D, it may be reduced byup to +3.00D. Undercorrectinghypermetropia appears to be standard

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An objective technique, which doesnot rely on a child’s verbal responses

and which can be used with even theyoungest patient is dynamicretinoscopy. It is a simple procedurethat can readily be incorporated into a

routine. The one described here(modified Nott retinoscopy) measuresthe accuracy of accommodation, notthe amplitude – arguably a more useful

measure for determining the need for arefractive correction. It has been shownto be a valid and repeatable techniquewhen compared with autorefractionmeasures of accommodation.16

Measure accommodation afterrefraction, so that the distancerefractive error is corrected, if

appropriate. Mount a detailed and

interesting picture on a near-pointrule. The most useful single distanceto place the target is at the child’shabitual working distance; theyounger the child (and the shorterher/his arms), the closer this will be.In the illustration (Figure 3) we have a

Perspex cube with a picture on eachface. Children tire of the same picturequickly, so it is useful to havealternatives. A self-illuminated targetmeans that the room lights can beturned down, making the retinoscopy

reflex easy to see. With a non-illuminated target, you may need theroom lights on, or try shining lightfrom the test chart onto the target sothat it is bright enough to grab the

child’s attention. We need to stimulateaccommodation, so talk about the

picture or ask the child questionsabout it, to maintain her/his attention.

Place the retinoscope alongside thetarget. Since distance refractive error

is corrected or negligible, we needonly look at one meridian of one eye.If the child is accommodatingaccurately to the target, then the reflex

seen alongside the target will beneutral - this is the optics of retinoscopy. If the child is over-accommodating, the reflex will be‘against’. In order to measure the

discrepancy or ‘lead’ of

accommodation, move the retinoscope

towards the child (keeping the targetstill) to find neutral. The dioptricdistance between neutral and thetarget will be the lead. Over-accommodation may indicate a binocular vision problem, and will

trigger further investigation of convergence etc.

If the child is under-accommodating,the reflex seen from alongside thetarget will be ‘with’. Move theretinoscope further from the child tofind neutral. The dioptric distance

between neutral and target will be the‘lag’ of accommodation. Generally, weaccept a lag of zero to 0.75D as withinthe normal range for children, using aviewing distance of 25cm17. A greaterlag may indicate a binocular visionproblem, or a difficulty inaccommodating accurately.

To use the above technique to

estimate the need for a hypermetropiccorrection, simply assess accuracy of accommodation uncorrected. If the lagexceeds 0.75D, then use partial

corrections of the hypermetropia untilthe lag is within the normal range.Rather than simple reliance on astandard under-correction of

hypermetropia, as suggested by thenote to Table 1, the use of dynamicretinoscopy allows us to determine themost suitable correction for anindividual child.

< Figure 3 Dynamic retinoscopy

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A myopic correction may leave achild struggling to accommodate for

near. This dynamic technique can beused to decide what advice to give achild on spectacle wear - full-time orfor distance use only.

Children with disabilitiesAmongst children with disabilities,accommodation difficulties are

common. Studies have shown that themajority of children with Down’ssyndrome (68%18) and children withcerebral palsy (58%19) show a large lagfor near targets (Figure 4).

These children are thereforehampered for close work in school bya blurred retinal image, even when

they are wearing their distance

correction for refractive error. Further,children with disabilities are muchmore likely to have refractive errorsthan are typical children (Figure 5),and so are in greater need of optometric eye care. Emmetropisation

is much less likely in children withdisabilities, for reason not yetunderstood, but poor accommodationmay play a role in preventing theusual emmetropisation process21. It isappropriate to prescribe refractivecorrection earlier for children with

disabilities, and to fully correcthypermetropia in all cases in whichaccommodation is compromised. If theaccommodation deficit remains inspite of distance correction, a near

is equal in the two eyes, the risk of

amblyopia is low; the child will have

clear vision for near tasks. Sinceyoung children have most, if not all of their interests at near, this means thatmyopia can be left uncorrected in theearly years. Once children get toschool, distance vision becomes more

important and myopia is bestcorrected.

As children approach adolescence,myopia becomes more prevalent, anddepending largely on ethnicity, can become quite common. There is aconsiderable research effort worldwide

in the field of myopia, but fulldiscussion of the theories of itsaetiology is beyond the remit of thisarticle, except to say that theaccommodative response to blur may be inefficient in the myopic eye.24,25

Here we will concentrate on thecorrection of myopia and the attemptto slow its progression. Bifocals,

progressives and contact lenses appearto have little clinical benefit in slowingmyopic progression. Some authoritieshave advocated under-correcting

myopia as a means of slowingprogression, but a recent study hasshown this approach to be counter-productive. Chung, Mohidon and

O’Leary26 compared myopiaprogression between two groups of 48children (9-14 years of age). One

correction should be considered.Children with Down’s syndrome

tolerate bifocals very well22 and onecase report showed that evenvarifocals have been successful incerebral palsy.23

Correction for myopiaAs we have seen, hypermetropia is themost common form of refractive error

amongst young children. Myopia isunusual in typical young children.When myopia does exist, providing it

< Figure 4 Accommodation in children (adapted from McClelland et al19 and from

Woodhouse et al 18 )

< Figure 5 Distribution of refraction in children (adapted from McClelland20 and from data

of the Cardiff Down’s Syndrome Vision Research Unit)

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group wore an under-correction (acuity

blurred to 6/12) while the other group

wore a full myopic correction. Myopiaprogression over a two-year period wassignificantly greater in the under-corrected group. The recommendationis for full correction for myopia, atleast for distance wear. A separate

study showed that removing spectaclesfor near work had no influence onmyopia progression27.

Dispensing for childrenAs for adult patients, spectacles canonly be successful if they are

comfortable and fit well, with thelenses situated appropriately.Children are, of course, also entitledto spectacles that look good.Generally, especially with today’sfashion for small metal frames,dispensing creates very few problems.Many frames have sides that are toolong; ensure that you carry stock

frames in which sides are adjustable.Keep different pads available.Depending on the size and shape of achild’s nose, button pads or strap

bridges may be more suitable than thestandard oval pads; be prepared tochange pads to suit individualchildren. Remember to take note of a

child’s eyelashes - a frame that sits tooclose to a child’s eyes may preventhim/her from blinking!

Some children are reluctant at firstto wear glasses. Some children dislikenew situations, and this appliesparticularly to children with learning

disabilities. Spectacle lenses providea focused image; we interpret this as

‘better’ but a child may interpret thisas ‘different’ and reject the glasses onthose grounds. Even if your eventualaim is full-time wear, don’t expect areluctant child to keep the glasses onall the time from the start. Discuss an

‘adaptation programme’ with theparent. The exact form will dependon the refractive error, the purpose of the spectacle correction and on thechild’s interests. Identify a favouriteactivity for which the spectacles aresuitable and during which the child

can have a parent’s (or other familymember’s) full attention. Make this‘spec wearing time’, and allow thechild to remove the glasses at the endof the activity. This way the child

learns to associate glasses with anenjoyable activity, and begins to

appreciate clearer vision for thatactivity. If the child is struggling tocope with the glasses, the activityshould be very short. Graduallyincrease the length of the activity,and/or introduce a second activity.

Reassure the parents that the processmay take weeks or even months (andanything shorter becomes a bonus)and above all, don’t make a parentfeel guilty or inadequate if this is aslow process. Similarly, don’t allowthe parents and child to turn it into a

battle – the child will win!Contact lenses can be a viable

alternative to spectacles for somechildren, but the topic is beyond thescope of this article.

SummaryRefraction in young children changesrapidly, in the usual case in the

direction of emmetropisation. A singlemeasure of refractive error, unlessextreme or anisometropic, is not auseful indicator of the need for

correction. Monitoring refractive errorat regular intervals will allow theoptometrist to distinguish betweeneyes that are emmetropising (low risk

of defects) and eyes that are not (highrisk of defects). If a child is in thehigh risk category, then correction forrefractive error is probably beneficial.

Hypermetropia in children may becompensated by activeaccommodation, but it is not sufficientto assume this. Practitioners should

measure accommodation routinely and

use this to determine the need for andthe amount of a hypermetropiccorrection, rather than rely onconsensus tables or usual practice.

Myopia should be corrected byschool age, (earlier if marked, or if the

child has distance interests) and befully corrected for distance.Accommodation can be measured todetermine whether spectacles may beworn for near tasks.

Finally, the refractive error cannot be considered in isolation. Binocular

vision status and visual acuity withoutand with a refractive correction will,of course, contribute to our decision-making, as will family history, and thewishes of both parent and child.

References1. Saunders KJ, Westall CA.

Comparison between near retinoscopyand cycloplegic retinoscopy in therefraction of infants and children.Optometry and Vision Science.1992;69:615-622.

2. Woodhouse JM, Pakeman VH,

Cregg M, et al. Refractive errors inyoung children with Down syndrome.Optometry and Vision Science.1997;74:844-851.

3. Mohindra I. A non-cycloplegic refraction technique forinfants and young children. Journal of

the American Optometric Association.1977;48:518-523.

4. Smith G. Refraction andvisual acuity measurements: what aretheir measurement uncertainties?Clinical and Experimental Optometry.2006;89:66-72.

5. Hirsch MJ, Weymouth FW.Prevalence of refractive anomalies. In:

Grosvenor, T, Flom, MC, eds.Refractive anomalies . Stoneham:Butterworth-Heinemann; 1991:15-38.

6. Larson JS. The sagittal growth

of the eye: IV Ultrasonic measurement of axial length from birth to puberty. ActaOphthalmologica. 1971;49:873-886.

7. Huynh SC, Wang XY,

Rochtchina E, Crowston JG, Mitchell P.Distribution of Optic Disc ParametersMeasured by OCT: Findings from aPopulation-Based Study of 6-Year-OldAustralian Children. Investigative Ophthalmology & Visual Science.2006;47:3276-3285.

8. Saunders KJ, Woodhouse JM,

Westall CA. Emmetropisation in

human infancy: Rate of change isrelated to initial refractive error. VisionResearch. 1995;35:1325-1328.

9. Wildsoet CF. Activeemmetropisation - evidence for itsexistence and ramifications for clinicalpractice. Ophthalmic and

Physiological Optics. 1997;17:279-290.10. Saunders KJ. Early refractive

development in humans. Survey of Ophthalmology. 1995;40:207-216.

11. Atkinson J, Braddick O,Nardini M, Anker S. Infant hyperopia:

Detection, distribution, changes andcorrelates - outcomes from theCambridge infant screening programs.Optometry and Vision Science.2007;84:84-96.

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12. Ingram RM, Gill LE, LambertTW. Effect of spectacles on changes of spherical hypermetropia in infantswho did, and did not, have

strabismus. British Journal of Ophthalmology. 2000;84:324-326.

13. Abrahamsson M, Fabian G,Andersson AK, Sjostrand J. Alongitudinal study of a population based sample of astigmatic children I:Refraction and amblyopia. ActaOphthalmologica. 1990;68:428-434.

14. Ingram RM, Gill LE, Goldacre

MJ. Emmetropisation andaccommodation in hypermetropicchildren before they show signs of squint - a preliminary analysis.Bulletin de la Société belge d'ophtalmologie. 1994;253:41-56.

15. Mutti DO. To emmetropize or

not to emmetropize? The question forhyperopic development. Optometry and Vision Science. 2007;84:97-102.

16. McClelland JF, Saunders KJ.The repeatability and validity of dynamic retinoscopy in assessing the

accommodative response. Ophthalmic and Physiological Optics.2003;23:243-250.

17. Rouse MW, Hutter RF. Anormative study of the

accommodative lag in elementaryschool children. American Journal of Optometry and Physiological Optics.1984;61:693-697.

18. Woodhouse JM, Cregg M,Gunter HL, et al. The effect of age,size of target and cognitive factors onaccommodative responses of childrenwith Down syndrome. Investigative Ophthalmology and Visual Science.2000;41:2479-2485.

19. McClelland JF, Parkes J, Hill

N, Jackson AJ, Saunders KJ.

Accommodative dysfunction inchildren with cerebral palsy: apopulation-based study. Investigative Ophthalmology & Visual Science.2006;47:1824-1830.

20. McClelland J:Accommodative dysfunction and

refractive anomalies in children withcerebral plasy, Faculty of Life andHealth Sciences. University of Ulster,Coleraine, 2004, pp. 309.

21. Stewart RE, Woodhouse JM,Cregg M, Pakeman VH. The

association between accommodativeaccuracy, hypermetropia andstrabismus in children with Down'ssyndrome. Optometry and VisionSciences. 2007;84:149-155.

22. Stewart RE, Woodhouse JM,Trojanowska LD. In focus: the use of bifocals for children with Down'ssyndrome. Ophthalmic and

Physiological Optics. 2005;25514-522.

23. Ross RM, Heron G, Mackie R,McWilliam R, Dutton G. Reducedaccommodative function in dyskineticcerebral palsy: a novel managementstrategy. Developmental Medicine and Child Neurology. 2000;42:701-703.

24. Gwiazda J, Thorn F, Bauer J,

Held R. Myopic children showinsufficient accommodative responseto blur. Investigative Ophthalmology and Visual Science . 1993;34:690-694.

25. O'Leary DJ, Allen PM.Facility of accommodation in myopia.Ophthalmic and Physiological Optics.

2001;21:52-55.26. Chung K, Mohidin N, O'Leary

DJ. Undercorrection of myopiaenhances rather than inhibits myopiacorrection. Vision Research.2002;42:2555-2559.

27. Ong E, Grice K, Held R,Thorn F, Gwiazda J. Effect of spectacleintervention on the progression of myopia in children. Optometry and Vision Science. 1999;76:363-369.

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Module questions Course code: c-5203Please note, there is only one correct answer. Enter online or by form provided

An answer return form is included in this issue. It should be completed and returned to CET initiatives (c-5203) OT ,Ten Alps plc, 9 Savoy Street, London WC2E 7HR by May 30 2007.

1. Which one of the following is NOT an advantage of the Mohindra retinoscopytechnique?a. Oculo-motor tests can be carried out on the same occasionb. Subsequent ophthalmoscopy is easierc. Binocular balance is more reliabled. There is no discomfort

2. Which one of the following is INCORRECT regarding the Mohindraretinoscopy technique?a. It is performed in total darknessb. It should be performed monocularlyc. Maximum pupil dilation should be achieved prior to neutralisationd. It should be performed binocularly

3. Which one of the following is INCORRECT regarding the repeatability ofrefractive error measurement?a. Repeatability is based on the standard error of the differences between

successive measuresb. Repeatability defines the confidence a practitioner may have in determining

a change in refraction over timec. Repeatability of Mohindra retinoscopy is less than 0.75Dd. Repeatability defines the likelihood that refractive error changes towards

emmetropia

4. Which statement is CORRECT? The process of emmetropisation:a. Means that children’s refraction becomes more hypermetropic with ageb. Can be impeded by leaving errors uncorrectedc. Is likely to be an active visually-driven processd. Results in most children having zero refraction by school age

5. Which statement is CORRECT regarding school-age children?a. 3-4% are anisometropicb. Approximately 26% have astigmatism of 1.00D or morec. 10-15% are myopicd. Approximately 2% are hypermetropic

6. Which statement is INCORRECT regarding strabismus and amblyopia?a. Children at risk will not have shown the usual reduction in refractive error

prior to the onset of the defectb. Both are highly associated with hypermetropiac. Children at risk can be best identified by monitoring refraction over timed. If refractive error increases over time, risk of strabismus and amblyopia is

minimal

7. Which statement is CORRECT regarding refractive errors in children?a. The higher the initial error, the faster the growth towards emmetropiab. Refraction is relatively static between birth and 12 monthsc. Emmetropisation is considered complete at two years oldd. Myopic errors at birth remain myopic

8. You carry out modified Nott dynamic retinoscopy with a child, setting thetarget at 25cm. You find ‘neutral’ at 40cm.What is the accommodative lag?a. 4.00Db. 2.50Dc. 1.50Dd. 1.00D

9. Which statement is INCORRECT regarding modified Nott dynamic

retinoscopy?a. A lead of more than 0.75D would indicate insufficient accommodationb. The technique informs decisions about a hypermetropic prescriptionc. The practitioner need only measure one meridian of one eyed. The target is best placed at the child’s habitual working distance

10. Which statement is CORRECT regarding children with disabilities?a. The peak of the refractive error distribution in cerebral palsy is -4Db. Children with Down’s syndrome tolerate bifocals very wellc. By school-age, children with disabilities have refractive errors similar to

typical childrend. Accommodation difficulties are rare

11. In order to minimise the progression of myopia in children, the best strategyappears to be:a. Do not correct until school ageb. Under-correct by around 1.00Dc. Give full correctiond. Provide bifocals

12. Which is the LEAST likely to encourage a child to wear glasses for the firsttime?a. Encouraging full-time wear to minimise the adaptation periodb. Fitting appropriately so that the frame stays in placec. Adopting a programme of gradual increases in wearing timed. Associating spectacles with a favourite activity

Please complete on-line by midnight on May 30 2007 -

You will be unable to submit exams after this date –

answers to the module will be published in our June 1 issue

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CET answers Course code: c-5199

These are the correct answers to Module 10 Part 4, which appeared in our April 6, 2007 issue

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1. The correct answer is C.

Neonatal misalignments should be becoming less frequent in the second month of

life.

2. The correct answer is B.

Nystagmus with an onset in adulthood is not a common feature of infantile esotropia

syndrome.


Epicanthus can co-exist with intermittent esotropia.

4. The correct answer is A.

Unlike the other options, a family history of primary open angle glaucoma is not a

significant risk factor for strabismus in young children.


Crowded Lea pictures are the best visual acuity test of those listed for detecting

strabismic amblyopia.


Of the options listed, a decompensated exophoria at near is the least significant

reason for carrying out a cycloplegic refraction in an 8 year old.

7. The correct answer is D.

There can be difficulties in detecting a microtropia with the cover test.


It is not appropriate for fully accommodative esotropia to be treated surgically.


Of the options given, the most accurate description of divergence excess intermittent

exotropia is a deviation that is greatest for far distance vision and the patient is

typically unaware because they suppress when the eye deviates.

10. The correct answer is D.

The most accurate of the statements is that the treatment of strabismic amblyopia is

associated with a high risk over the age of 7-8 years.


The most accurate of the statements is that where there is a significant refractive

error, the first stage of amblyopia treatment is refractive correction.

12. The correct answer is B.

It is not true to say that a lateral rectus palsy usually causes most symptoms during

near vision. This type of palsy usually causes maximum diplopia in distance vision,

when looking to the side of the affected muscle.

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